Using and Passing input files to functions

Question

I have an input files with chars (grades) in it and am trying to input them into an array using functions and input files. I don't beleive I am declaring / passing the input file (iFile) correctly. Any help with my sytax and parameters would be great.

Error(s): 'std::basic_streambuf<_CharT, _Traits>::basic_streambuf(const std::basic_streambuf<_CharT, _Traits>&) [with _CharT = char; _Traits = std::char_traits]' is private

#include <iostream>
#include <iomanip>
#include <fstream>
using namespace std;

void readInput(char gradeArray[][3], ifstream iFile);
void spitOutpt(char gradeArray[][3], ifstream iFile);

int main()
{
    ifstream iFile;
    iFile.open("grades.txt");
    char gradeArray[5][3];

    readInput(gradeArray, iFile);
    spitOutpt(gradeArray, iFile);

    return 0;
}

void readInput(char gradeArray[][3], ifstream iFile)
{
    for(int r = 0; r < 5; r++)
        {
            for(int c = 0; c < 3; c++)
            {
            iFile >> gradeArray[r][c];
            }
        }

    return;
}

void spitOutpt(char gradeArray[][3], ifstream iFile)
{
    cout << "All Grades" << endl;
    cout << left << setw(10) << "Student";
    cout << left << setw(10) << "English";
    cout << left << setw(10) << "History";      
    cout << left << setw(10) << "Math";
    cout << endl;


    for(int r = 0; r < 5; r++)
        {
        cout << "#" << left << setw(10) << r;
            for(int c = 0; c < 3; c++)
            {
            cout << left << setw(10) << gradeArray[r][c];
            }
        cout << endl;
        }

    return;
}

R Sahu · Accepted Answer · 2016-09-02 19:44:32Z

2

Pass std::ifstream and std::ofstream by reference.

They don't have copy constructors.

void readInput(char gradeArray[][3], ifstream& iFile);
void spitOutpt(char gradeArray[][3], ifstream& iFile);

Suggestion for cleanup

Your use of ifstream as argument to spitOutpt does not seem right. Perhaps you meant that to be an ofstream.

void spitOutpt(char gradeArray[][3], ofstream& oFile);

and then change main to:

int main()
{
    ifstream iFile;
    iFile.open("grades.txt");
    char gradeArray[5][3];

    readInput(gradeArray, iFile);


    ofstream oFile;
    oFile.open("grades-out.txt");
    spitOutpt(gradeArray, oFile);

    return 0;
}

answered Sep 2, 2016 at 19:44

R Sahu

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4 Comments

Stubbsy Over a year ago

Thank you. Why is that? Never really understood what 'copy constructors' and 'passing by value/reference' truly mean.

R Sahu Over a year ago

@Stubbsy, why is what?

Stubbsy Over a year ago

@R Sahu, sorry for the very basic questions. Only my 2nd week at this. Why does the & make it work? I understand its use but not it's true definition. Thanks again.

R Sahu Over a year ago

When the argument type is ifstream&, the input argument is passed as a reference, not by value. Passing by value will make a copy. Passing by reference does not make a copy.

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